(CNSNews.com) -- In questioning Homeland Security Secretary Janet Napolitano, Sen. Claire McCaskill (D-Mo.) drew a parallel between the explosions, injuries, and deaths at the Boston Marathon with the gunfire massacre at the Sandy Hook Elementary School, and asked why it also is not designated as an act of terror.

McCaskill also hesitated calling what happened in Boston an act of terror, saying in part, “We are so quick to call Boston terror.”

At a hearing of the Senate Committee on Homeland Security and Governmental Affairs on Wednesday, McCaskill said, “But I’m a former prosecutor and I’ve got a question that is just—I can’t keep it from coming out. Based on the evidence at this point, is there any difference between Sandy Hook and Boston other than the choice of weapon?”

Napolitano said: “Well, in terms of intent for death and destruction and injury, no. Methodology, yes. And we don’t know the motivation behind certainly Boston. We don’t [know] whether it was domestic, international –”

McCaskill: “Or if it was identical to the motivation in Sandy Hook?”

Department of Homeland Security Secretary Janet Napolitano. (AP)

Napolitano: “We just don’t know the answers to those questions. So, I think that it’s impossible for me to sit at the table today and say they are identical except in effect and impact.”

“Well, as I look at the evidence that’s available, you have mass destruction and violence and slaughter of innocents. And in neither case do we know motive,” McCaskill told Napolitano.

“And the irony is we are so quick to call Boston terror, why aren’t we calling the man with the high capacity assault weapon and the high-capacity magazine, why aren’t we calling him a terrorist?” she asked.

Napolitano replied that she did not know the answer to McCaskill’s question, at which point McCaskill questioned why the attack at the Boston Marathon has been labeled by U.S. Government officials as an act of terror when the Sandy Hook shooting was not labeled an act of terror.

“But as I look at with the eye of a prosecutor and the evidence that is available right now, I find it troubling that one is characterized in a way that causes so much more fear and disruption in everyone’s daily lives than the other one,” McCaskill told Napolitano.

Two men in haz-mat suits investigate the scene of the first bombing on Boylston Street in Boston Tuesday, April 16, 2013 near the finish line of the 2013 Boston Marathon, a day after two blasts nearby killed three and injured over 170 people. (AP Photo/Elise Amendola)

“It just is troubling to me and I think both of them, maybe they have identical motives,” she said. “One chose a military style weapon with a high-capacity magazine and the other one chose to make a homemade bomb.”

On Monday, two bombs exploded near the finish line of the Boston Marathon, killing three people —one an eight-year-old boy -- and injuring over 170 people. Officials also found two more explosive devices that did not detonate.

On Dec. 14, 2012, Adam Lanza killed his mother and then shot and killed 26 other people at Sandy Hook Elementary School in Newtown, Conn. -- 20 of whom were children -- before killing himself.

On Tuesday, President Obama called the Boston attack an "act of terror," saying, “Any time bombs are used to target civilians, it is an act of terror"

In her final remarks to Napolitano, Senator McCaskill said, “I think it’s important that we talk about that in government. And it may be that we learn the motive of both [Boston and Sandy Hook] and maybe the motive in Sandy Hook was political and the motive wasn’t. Or the motive in Boston was political, and the motive in Sandy Hook wasn’t. It may be they both [the killers] are suffering from severe mental incapacity that caused them to want to go slaughter a bunch of innocent people.

“But as I look at with the eye of a prosecutor and the evidence that is available right now, I find it troubling that one is characterized in a way that causes so much more fear and disruption in everyone’s daily lives than the other one -- ot that there aren’t mothers all over the country that are afraid to send their first graders to school these days, there are. But I would certainly urge you, secretary, to take a look at this and see if the government has a responsibility as to when and how we characterize an act, a criminal act, an act of terror when there is not evidence yet to support I believe that characterization, until we know what the motive is. It just is troubling to me and I think both of them, maybe they have identical motives.”